Mask-wearing revelers during the the Banda de Ipanema Carnival parade. Streets across Brazil have been swamped with Carnival revelers, with the largest parties attracting more than 1 million merrymakers. Silvia Izquierdo, AP

'King Momo' holds up the key to the city, given to him by Rio de Janeiro Mayor Eduardo Paes, right, during the official opening of the Rio Carnival. The ceremony begins five days of celebration. Yasuyoshi Chiba, AFP/Getty Images

Dancers from the Unidos de Vila Isabel samba school, which won the festival's fiercely competitive samba contest last year, perform during the opening of Rio Carnival. Yasuyoshi Chiba, AFP/Getty Images

A traditional character of Rio Carnival, 'King Momo,' receives the key to the city from Río de Janeiro Mayor Eduardo Paes during the opening ceremony of Carnival. Antonio Lacerda, European Pressphoto Agency